It is well known that the frequency of transformation of a cell, whether prokaryotic, for example Escherichia coli l (E. coli), or eukaryotic, for example Saccharomyces cerevisiae (S. cerevisiae), by plasmids is relatively small. Thus, it is desirable to include, within the genome of the transforming plasmid, certain characteristics which may be used to identify transformed cells. Such identification characteristics are known within the art as markers and may include specific nucleotide sequences, drug resistance, including antibiotic resistance, characteristics, or the ability to synthesize specific growth factors, for example amino acids, which the non-transformed host cell cannot otherwise synthesize.